^God^Air^
May 18th, 2002, 07:35 PM
Im kinda new hear and I did alot of reading and It seems like alot of people are new to bikes. I wrote out a suspension tutorial to help people out, some who have problems and some who dont know they have problems.. so take the time to read through if you feel you dont quite understand how suspension and the geometry of a bike.
<b>Ill start off with the rear shock..When you buy a new bike the biggest adjustment you can make to the bike is the rear shock. The forks usually come dialed in pretty much as good as your going to get it.. except a few things.
First off.. race sag. This is a very important part of how the bike controls. When the bike settles down with you on it.. it lays the weight to the back tire and changes the geometry of the bike by increasing the angle of the forks. It basically tilts the bike back. When the forks have a greater angle it gives the bike better stability<i>(kind of like a low rider harly with the loonng forks[youd never get head shake on that bike])</i>, in high speedbumpy,sandy, and pretty much all areas. If your rear shock spring is set too stiff, the bike will tend to lean forward when cornering, braking and hitting bumps on a long strait ...therefore decreasing the fork angle and making the bike less stable and this will cause head shake and have the front end slide out.
So you want to set the spring to a 90-100mm sag for your specific body weight for the best of both worlds. Start off by putting the bike up on a stand and measure the distance from the center of the axle bolt to somewhere on the rear fender, use some tape or whatever so you make sure you measure from the same 2 spots each time.
write down that distance(pick a spot on the rear fender that gives your a good number like 600mm and try to make it strait up and down as you can.) then with all your gear on.. sit on the middle of the seat where you normally would sit and have someone measure the new distance between the 2 points again. Write down the new distance.. When you subtract the sag distance with you on it from the distance when it was on the stand it gives you the race sag measurment.. Tighten or loosen the spring to get a sag difference from complete extension to the sag with your weight on it from around 90-100mm. (85-90mm will give you a tighter and better stearing but will cost you some high speed stability, 95-105mm sag will give you better control and stability but will slightly lower the tight stearing abilities)
Now here is the tricky part, after you get the spring set properly. measure the distance that the bike sags from when its on a stand, to how much it sags down when its sitting on level ground with no rider just its own weight (this is the free sag). If the bike sags more than 30mm than your spring is too hard for your weight.. this is sounds backwards but its true. Its because in order to get the bike to sag enough with your weight on it you really have to loosen the spring tension so when you get off.. the spring is so loose the bike sags to far by itself. now if the bike doesnt sag at all this means your spring is too soft for your body weight. this is because you set the spring tension so hard to have it support a 95-100mm sag that when you get off the spring pushes the bike all the way back up. Doing this tells you if you are too heavy or too light for the spring on your bike. the correct free sag is 10-30mm.
now for the compression adjusters on the rear shock.
here is a scenario: you go over a series of bumps.. the bike handles the first 5 or so bumps fine but at the last 3 bumps the bike kicks up in the air really hard and high. You might think. well jeeze its kicking so much i should increase the rebound damping because its extending to quickly.. you go out and it does it even worse this time.. you cant seem to figure out why..
The reason: The problem here is the rebound damping is actually set to stiff. as the bike goes over the bumps it starts to soak up the bump and the suspension moves up, it hits the next bump and moves up even more.. but because there is too much rebound damping the shock never has time to kick back out.. each bump it hammers up further untill it finally hits its final travel the then makes the bike kick up in the air. If you loosen off the rebound damping and go out and try it again you will find that the suspension is absorbing each bump and extending all the way out between each bump.
you should set the rebound damping adjuster to where your manual says and after a few laps decide if you think it needs a little more or less. and only change it by 2 clicks the most. there is a small window that you can actually adjust without drastically changing the bikes handling so dont click it too much.
low speed compression adjuster doesnt nescesaraly change how the bike reacts to low speed bumps but what it does is adjust the compression damping for a cirtain stroke range of the shock.. it affects the first 1/3 or so the travel. If the bike feels a little harsh when going through some braking bumps or exiting a rutted bumpy corner you can try adjusting it.
The high speed adjuster changes the damping of the shock through its full stroke. if you think the bike bottoms out too harshly adjust the high speed adjust by 1/2 to 1full turn increments.
set it to the manuals specefications and try it out before making any changes.
Now for the forks....
One thing you can do to ajust the bikes geometry and handling under different circumstances is raise or lower the forks equally in the tripple clamps. When you Raise the forks/lower the bike it again decreases the forks angle this will give you a better tighter steering for small and tight tracks but may cause you to loose some strait line stability and make the bike swap and shake at higher speeds or in muddy/sandy conditions.
Lowering the forks/raising the front end of the bike increases the fork angle and again gives the bike a greater stability at high speeds and in soft dirt, although it will slightly decrease tight cornering ability.
The thing you want to go for here is usually stability, thers nothign worse than a bike that wanders all over the tracks and bobbles and head shakes your hands off the bars.. if you do notice the bike lose some tight steering abilities try and shift your weight even more forward on the bike when you are conrering and push down perpendicular to the ground(meaning a vertical force towards the ground) on the outside footpeg, this is the trick to traction on corners it flexes the sidewalls on the tires and adds more downwards force to the suspension and tires instead of a sideways force.
If you find out that your rear shock spring is drastically to soft then you will also want to get a set of fork springs to match the new stiffer rear shock that you purchace for your weight.
the same goes for the adjusters on the forks.. if your going through some big bumps or whoops and you find that nearing the end of the bumps/whoops the front end of the bike hits too hard and jars your hands it is most likely because there is too much rebound damping and the fork gets stuck bottomed out nearing the end of the bumps.
you want to set the compression and rebound damping clickers to the manuals specifictions and modify them seperatly in 1-2 click incraments out on the track. meaning: start by adjusting the compression damping softer or harder untill you like how it feels before adjusting the rebound damping.. if you start changing both at the same time you cant tell what affected what..
Basically out of all this info.. I went out and set my bike up for stability, and a bit of a loss of tight cornering. now my bike almost never swaps, kicks, shakes or does the chicken no matter what I ride through..
its amazing!.. Because i weight about 155lbs with all my gear on.. the stock springs didnt need to be changed, the springs are designed for a rider 150-170lbs.. If your not in that range you are really missing out on what a bike is supposed to be like.
</b>
:)
<b>Ill start off with the rear shock..When you buy a new bike the biggest adjustment you can make to the bike is the rear shock. The forks usually come dialed in pretty much as good as your going to get it.. except a few things.
First off.. race sag. This is a very important part of how the bike controls. When the bike settles down with you on it.. it lays the weight to the back tire and changes the geometry of the bike by increasing the angle of the forks. It basically tilts the bike back. When the forks have a greater angle it gives the bike better stability<i>(kind of like a low rider harly with the loonng forks[youd never get head shake on that bike])</i>, in high speedbumpy,sandy, and pretty much all areas. If your rear shock spring is set too stiff, the bike will tend to lean forward when cornering, braking and hitting bumps on a long strait ...therefore decreasing the fork angle and making the bike less stable and this will cause head shake and have the front end slide out.
So you want to set the spring to a 90-100mm sag for your specific body weight for the best of both worlds. Start off by putting the bike up on a stand and measure the distance from the center of the axle bolt to somewhere on the rear fender, use some tape or whatever so you make sure you measure from the same 2 spots each time.
write down that distance(pick a spot on the rear fender that gives your a good number like 600mm and try to make it strait up and down as you can.) then with all your gear on.. sit on the middle of the seat where you normally would sit and have someone measure the new distance between the 2 points again. Write down the new distance.. When you subtract the sag distance with you on it from the distance when it was on the stand it gives you the race sag measurment.. Tighten or loosen the spring to get a sag difference from complete extension to the sag with your weight on it from around 90-100mm. (85-90mm will give you a tighter and better stearing but will cost you some high speed stability, 95-105mm sag will give you better control and stability but will slightly lower the tight stearing abilities)
Now here is the tricky part, after you get the spring set properly. measure the distance that the bike sags from when its on a stand, to how much it sags down when its sitting on level ground with no rider just its own weight (this is the free sag). If the bike sags more than 30mm than your spring is too hard for your weight.. this is sounds backwards but its true. Its because in order to get the bike to sag enough with your weight on it you really have to loosen the spring tension so when you get off.. the spring is so loose the bike sags to far by itself. now if the bike doesnt sag at all this means your spring is too soft for your body weight. this is because you set the spring tension so hard to have it support a 95-100mm sag that when you get off the spring pushes the bike all the way back up. Doing this tells you if you are too heavy or too light for the spring on your bike. the correct free sag is 10-30mm.
now for the compression adjusters on the rear shock.
here is a scenario: you go over a series of bumps.. the bike handles the first 5 or so bumps fine but at the last 3 bumps the bike kicks up in the air really hard and high. You might think. well jeeze its kicking so much i should increase the rebound damping because its extending to quickly.. you go out and it does it even worse this time.. you cant seem to figure out why..
The reason: The problem here is the rebound damping is actually set to stiff. as the bike goes over the bumps it starts to soak up the bump and the suspension moves up, it hits the next bump and moves up even more.. but because there is too much rebound damping the shock never has time to kick back out.. each bump it hammers up further untill it finally hits its final travel the then makes the bike kick up in the air. If you loosen off the rebound damping and go out and try it again you will find that the suspension is absorbing each bump and extending all the way out between each bump.
you should set the rebound damping adjuster to where your manual says and after a few laps decide if you think it needs a little more or less. and only change it by 2 clicks the most. there is a small window that you can actually adjust without drastically changing the bikes handling so dont click it too much.
low speed compression adjuster doesnt nescesaraly change how the bike reacts to low speed bumps but what it does is adjust the compression damping for a cirtain stroke range of the shock.. it affects the first 1/3 or so the travel. If the bike feels a little harsh when going through some braking bumps or exiting a rutted bumpy corner you can try adjusting it.
The high speed adjuster changes the damping of the shock through its full stroke. if you think the bike bottoms out too harshly adjust the high speed adjust by 1/2 to 1full turn increments.
set it to the manuals specefications and try it out before making any changes.
Now for the forks....
One thing you can do to ajust the bikes geometry and handling under different circumstances is raise or lower the forks equally in the tripple clamps. When you Raise the forks/lower the bike it again decreases the forks angle this will give you a better tighter steering for small and tight tracks but may cause you to loose some strait line stability and make the bike swap and shake at higher speeds or in muddy/sandy conditions.
Lowering the forks/raising the front end of the bike increases the fork angle and again gives the bike a greater stability at high speeds and in soft dirt, although it will slightly decrease tight cornering ability.
The thing you want to go for here is usually stability, thers nothign worse than a bike that wanders all over the tracks and bobbles and head shakes your hands off the bars.. if you do notice the bike lose some tight steering abilities try and shift your weight even more forward on the bike when you are conrering and push down perpendicular to the ground(meaning a vertical force towards the ground) on the outside footpeg, this is the trick to traction on corners it flexes the sidewalls on the tires and adds more downwards force to the suspension and tires instead of a sideways force.
If you find out that your rear shock spring is drastically to soft then you will also want to get a set of fork springs to match the new stiffer rear shock that you purchace for your weight.
the same goes for the adjusters on the forks.. if your going through some big bumps or whoops and you find that nearing the end of the bumps/whoops the front end of the bike hits too hard and jars your hands it is most likely because there is too much rebound damping and the fork gets stuck bottomed out nearing the end of the bumps.
you want to set the compression and rebound damping clickers to the manuals specifictions and modify them seperatly in 1-2 click incraments out on the track. meaning: start by adjusting the compression damping softer or harder untill you like how it feels before adjusting the rebound damping.. if you start changing both at the same time you cant tell what affected what..
Basically out of all this info.. I went out and set my bike up for stability, and a bit of a loss of tight cornering. now my bike almost never swaps, kicks, shakes or does the chicken no matter what I ride through..
its amazing!.. Because i weight about 155lbs with all my gear on.. the stock springs didnt need to be changed, the springs are designed for a rider 150-170lbs.. If your not in that range you are really missing out on what a bike is supposed to be like.
</b>
:)